I have been hearing quite a bit about how sli doesn't offer much performance advantage, but looking at 3dmark06 benches, there is clearly a 60-70% advantage in having a second card-- Is this becasue this benchmark is optimized for SLi or can you expect that kind of boost for games too? Anyway this new SLi is supposed to be an improvement in that it takes 4,6, or even 8 cards, and they can supposedly be different cards- hey why not?

Nvidia Corp., the world’s leading supplier of discrete graphics processing units (GPUs), is reportedly planning to update its multi-GPU SLI technology in March to enhance performance and features, thus making SLI more appealing to computer enthusiasts.
The so-called Nvidia SLI 2.0 technology – which, according to a news-story over VR-Zone web-site should be unveiled at CeBIT 2007 – should support work of 4, 6 and 8 graphics chips in parallel as well as support different graphics card’s operation in tandem. There are currently no clear details regarding the SLI 2.0, but the fact that Nvidia is looking forward to improve its multi-GPU technology deserves attention.
Nvidia originally introduced its SLI multi-GPU technology in mid-2004 and shipped first platforms to support it in late 2004. While initially the technology had certain compatibility and performance limitations, eventually Nvidia made possible to use two graphics cards based on the same GPU from different suppliers and with different amount of onboard memory together. Moreover, in early-2006 the firm introduced so-called quad SLI technology, which allowed four GPUs to work together. In addition, the company said that graphics cards will be able to use their processing power to compute advanced physics effects once games support it.
But despite of many advantages that SLI has, not a lot of *****s actually use multi-GPU systems. Only about 12.7 thousand of 850 thousand of respondents – or about 1.5% – had a multi-GPU personal computer (PC) with either two, three or four graphics processors, the stats at Steampowered web-site reveal. But Nvidia’s SLI (scalable link interface) technology is far more popular than ATI’s CrossFire. Steam hardware survey indicates that there are 12.1 thousand multi-GPU systems – or about 96% – with two GeForce chips and only around 500 computers – or 3.9% - 4.0% – that feature two Radeon GPUs.
It is interesting to note that the system reports about 4 owners of 3-way SLI machines and 2 proud owners of quad SLI systems with four GeForce chips inside. Given that the survey hardly makes difference between the cards, but checks whether a multi-GPU tech is enabled in the driver, the dual-chip GeForce 7950 GX2 graphics cards should be considered as a computer with two graphics accelerators.